The field of this invention is related to electro-chemistry and particularly to the electro-chemical milling of metallic parts.
The use of cutting tools, such as drills, routers, reamers and the like, are in extensive widespread usage. A typical cutting tool is sharpest when initially purchased. The shape of the cutting edge has been pre-established at the factory and is honed to be as sharp as possible. This cutting tool is then utilized at a finished stage of production. As the tool dulls, the tool is then utilized at a final roughing out stage. When the tool further dulls it is then moved to be utilized at an initial roughing out stage which is frequently termed "hogging". When the tool becomes unusable at this stage, the tool is either discarded or resharpened.
Such tools are reasonably expensive. If a tool can be resharpened and reused, generally that would be the most economical course of action. Generally, this resharpening costs approximately one-half the initial cost of the tool. This resharpening is accomplished manually utilizing a grinding technique. There are machinists that specialize in resharpening of tools.
The resharpened tool is normally used at the finishing stage. As the tool dulls, it is then moved to the "hogging" out stage. Resharpening significantly extends the life of the tool.
There are certain disadvantages to this manually resharpening of tools. The first disadvantage is that it is a reasonably expensive operation. The second disadvantage is that it is time consuming and normally requires that the tool is shipped to an outside location from its point of usage and is gone for a period of time during which it is resharpened. The third disadvantage is that the resharpening technique is accomplised frictionally. As a result, a significant amount of material is removed from the tool. If the tool is cylindrical, the diameter of that tool is significantly reduced, generally in the range of three to five percent. Because of the amount of material that is being removed, the tool can only be resharpened a few times before it becomes non-usable.
Previously, electro-chemical milling is well-known and comprises the removal of material from the surface of a metal piece by the application of an electrical potential in the presence of a conductive electrolyte. This electrical chemical milling process is particularly well suited to imparting a smooth finish to parts having surface irregularities. In the past, electrical chemical milling has been utilized to deburr a manual or mechanically sharpened edge, or in certain instances actually creating a sharpened edge on a cutting tool. This process has found itself well suited for resharpening of a file and in certain instances it has been utilized to sharpen a cutting edge when utilized in conjunction with a protective film applied to a portion of the tool that is being resharpened. However, prior to the present invention it is believed that it has not been known to utilize the electro-chemical process solely for resharpening cutting edges.